A Conference in Memory of Prof. Roman Juszkiewicz

a scientific meeting commemorating Roman Juszkiewicz to be held in Zielona Gora 27-29 January 2013.

The meeting program

Sunday 27th:

Monday 28th:

09:30am - pick up from the Srodmiejski hotel.10:00 - 10:30 - Inauguration of a new seminar hall dedicated to
memory of Prof. Roman Juszkiewicz by President of the University Prof. Tadeusz Kuczyński10:30 - 12:00 - Recollections of Staszek Bajtlik about Roman 12:00 - 13:00 - lunch13:00 - 14:00 - presentations of videos and talks sent by Roman’s friends who could not attend the meeting.14:00 - 15:00 - Seminar talk by prof. Joe Silk - "On Roman Juszkiewicz scientific contributions in the context of the modern cosmology."19:00 - Gala dinner at Palmiarnia (The Zielona Góra Palm House)

Tuesday 29th:

In the present-day Universe, the effect of gravity on small perturbations is
easy to predict using linear perturbation theory. Conversely, clustering is
easy to measure on small scales where perturbations are nonlinear and further
complicated by the bias between mass and tracer populations. Roman was long
interested in how to reconcile the differences between the predictions and
data on a variety of scales by bringing together a variety of theoretical
observational tools. I will discuss some of this work, concentrating upon the
use of sigma_8 as a diagnostic of clustering strength.

I will review standard and exotic cosmological singularities which
attracted a lot of interest recently. Only some of them are singularities
in the sense of standard definition of singularity given by geodesic
incompletness. Instead, they have various geometrical and physical
quantities divergent. Then, I will discuss if some of these singularities
can be weakened, strengthened, or avoided due to the time-variation of the
fundamental constants such as G or c.

I will present and discuss the results from a study devoted to the sensitivity
of the hierarchical amplitudes of cosmic density and velocity fields to
the underlying laws of gravity. This is done under assumption that the
observed large-scale structure of the Universe grown from tiny Gaussian
initial conditions due to the gravitational instability mechanism. I will also
discuss how modified gravity strongly impacts large-scale peculiar velocity
fields in terms of it's power spectrum and shear and vorticity components.

I will give an overview of estimating correlation functions of cosmological
galaxy distributions. I will describe the error sources (discreteness, cosmic
noise) and ways to handle these. I will present in detail a novel method for
estimating discreteness errors by block bootstrap.

Roman's major interests were in non-linear evolution of cosmological
gravitational instabilities. I am going to discuss two examples of
non-linear effects in another type of instability, that of hydrodynamic
accretion in the gravitational field of stellar remnants
(white dwarfs, neutron stars and black holes).
The first example, backflows in accretion disks, holds equally well
in Newtonian gravity and in general relativity.
The second example, non-linear resonance of epicyclic modes in accretion
torii, can occur in general relativity, and may explain the so called twin kHz
QPOs in neutron star and black hole systems.

I will concentrate on the view of the large scale structure of
the Universe emerging from the analysis of different types
of galaxies in the modern deep redshift surveys.
In particular, the results expected from the VIMOS Public
Extragalactic Redshift Survey (VIPERS) - the largest
spectroscopic survey of galaxies at z~1 up to date -
will be discussed.

Among many projects that Roman Juszkiewicz was involved in, measurements of
the cosmic density parameter stand out. I will describe three main ideas how
to dynamically measure the mean density of matter in the Universe, to which
Roman contributed significantly. These are: comparison of the peculiar
velocity and acceleration of the Local Group; mean pairwise streaming velocity
of galaxies; skewness of the velocity divergence field. All these methods have
been applied in the past, including by Roman and his collaborators, and helped
to exclude the once popular Einstein-de Sitter model, well before WMAP
results. They still have great future prospects as independent tests of the
viability of the LambdaCDM model.

16:40 - 17:00 Summary and discussions.
We also plan to publish proceedings of the conference containing talks given by the participants as well as the materials sent by those colleagues and friends of Roman who could not personally attend the meeting.